For example, in an X-ray spot-shot system, if a gap such as an air gap is present between an X-ray film and intensifying screen sheets, a roentgenogram with high quality cannot be expected.
In order to eliminate such a gap, a conventional X-ray film holding apparatus shown in FIG. 1 is proposed (Japanese Patent Disclosure (Kokai) No. 154296/83). The holding apparatus comprises opposite front and rear plates 2 and 4. The front plate 2 has flexibility and is fixed and supported on a frame 6. The front plate 2 is curved and extends toward the rear plate 4. A flat cushion member 8 is mounted on the rear plate 4. Intensifying screen sheets 10 are respectively adhered to the front plate 2 and the flat cushion member 8.
Since the cushion member 8 is flat in the above holding apparatus, air is trapped between the X-ray film and the intensifying screen sheets 10, and the film cannot be brought into tight contact with the screen sheets 10. As a result, the sharpness of the roentgenogram is degraded. Even after the film is brought into contact with the screen sheets 10, no pressure gradient between the front plate 2 and the cushion member 8 occurs (i.e., an isobaric distribution is obtained), and air cannot be removed from the space between the film and the screen sheet.
In order to remove the gap, another X-ray film holding apparatus is also proposed, as shown in FIGS. 2 and 3 (Japanese Patent Disclosure (Kokai) No. 22805/83). In the holding apparatus, semicylindrical cushion members 16 are respectively mounted on opposite surfaces of front and rear plates 12 and 14 coupled by a hinge at the corresponding edges thereof. The generatrices of the members 16 are perpendicular to each other. Intensifying screen sheets 18 are respectively adhered to the upper surfaces of the cushion members 16.
Since one of the cushion members 16 is also mounted at the side of the front plate 12, the front plate 12 is spaced apart by several millimeters from the X-ray film. For this reason, magnification of an object to be photographed is increased, and sharpness of the image is degraded. In addition, since the members 16 are respectively mounted on the plates 12 and 14, the plates 12 and 14 must be opened widely to load the X-ray film, thus resulting in a bulky apparatus.